Powerful automatic exposure range to 70 ft. Guide Number: 120 (ISO100/ft.). * Control flash distance range and depth of field with four auto f/stop settings. * Auto ThyristorT circuitry for more flashes and faster recycle time. * Vertical bounce flash for softer, professional quality lighting. * Built-in variable power for convenient fill flash and rapid sequence photography. * Removable sensor for off-camera automatic flash with optional cord.